Aerodynamics vs. Appearance

I get on average 6.1-6.2 with this ol 97 379 pete with a 12.7 detroit. I run 500 miles a trip bout 400 highway and 100 city driving. I run around 65 mph works out good for me.

 

^^Good looking truck too

 

Very true. You can't get efficiency from aerodynamics with large trailer to cab air gaps.
Best spec would be minimal fuel tanks and get that trailer close to the cab, tight as possible to the fairings like a euro truck.
For now a windbreaker would be a good cheap addition to the top of the front of his trailer as you suggested. Also consider side skirts on the trailer.

 

You are proof that mileage has a lot more to do with driver skill than technology. You running 80k mostly? Flat ground or hilly?

 

Yes I run right around 80k and mostly flat with a few hills here and there. The mpg I see is based on my right foot and watching the tach. I know the sweet spot in my truck. I have days I'll run it harder if I need to make some time up ect. Otherwise she's happy at 65 crusing down the highway.

 

And when it's your money you pay attention to the fuel mileage. Those company drivers don't care because it's not there coin.

 

I agree. I'd go with a lift axle on the trailer and a single screw on your drive axles. Maybe even lift a drive axle.

 

Depends on the driver. I'm a company driver and keep idle time to a minimum, run in the sweet spot and do my best to slow down rather than stop for lights since the money the company saves on fuel could possibly end up being passed on my way come raise time. And they track the fuel economy of all their trucks.

 

Yeah probably a pusher drive with the front rear being liftable like the new adaptive load Volvo and Mack trucks are using. Of course if you were going Mack or Volvo I'd go XE or Econodyne on the spec.....and add that adaptive load lift axle to the spec. Fleets are reporting a .5mpg improvement when lifted during light operation over a traditional tandem....and no traction Loss like the old pusher or puller single screw drives.

As a reference, most truck cap haulers run 6.2-6.8 mpg. My Q1 2016 IFTA was 7.65 mpg with the XE package that turns 1150@65mph. About a full mpg over my old truck.

 

Going with lift axle seems to make sense, and that was part of Kevin Rutherford's signature glider. The truck got good mileage, but about what you could do if you modified a brand new truck, not what you would expect for a truck that was built for mileage. Because of the wheelbase for the single axle rear, Kenworth insisted it be double framed. The truck spec'ed for mileage weighed 23,000 lbs! What the gained by having the lift axle, they lost by the extra weight.